Here at SocketLabs we spend a lot of time policing our network to protect it from abuse. Abuse can come in many forms including, but not limited to, malicious users, compromised systems, poor list acquisition techniques, bad affiliates, etc. Not all abuse is treated equally and we spend a lot of time blocking the bad stuff while allowing good messages to flow.
With our email abuse protection, every email that enters our network is examined using several techniques such as custom spam scanning, 3rd party spam scanning, public and private black lists, and a signature/pattern matching system. with email abuse protection, we can also monitor feedback from the mailings themselves and use a reputation system to find accounts that are behaving badly.
When a malicious user creates an account and is blatantly sending spam we can easily suspend their server and eventually cancel their service. When the malicious mail stream is mixed with legitimate email the problem becomes more difficult. We are aggressively adding improvements that give us the ability to block the bad messages without interrupting the good mail. This gives the customer time to investigate and correct the problem while still sending their legitimate email. Some of these things include allowing the end user to pause their server, deleting messages based on domain or based on the message id, only allowing messages from specific from addresses, or simply blocking mail from specific email addresses.
This is just another way we are protecting your email and improving our systems behind the scenes to help maintain the reputation of both for your domain and for the IP address on which your mail is delivered.